JP4509358B2

JP4509358B2 - Intermediate transfer member and method for producing the same

Info

Publication number: JP4509358B2
Application number: JP2000346745A
Authority: JP
Inventors: 誠草柳; 誠司荻原; 俊彦富田; 喜一郎松下; 時男藤田
Original assignee: Fuji Xerox Co Ltd; Nitto Denko Corp; Fujifilm Business Innovation Corp
Current assignee: Nitto Denko Corp; Fujifilm Business Innovation Corp
Priority date: 2000-11-14
Filing date: 2000-11-14
Publication date: 2010-07-21
Anticipated expiration: 2020-11-14
Also published as: JP2002148899A; US6751434B2; US20020141784A1

Description

【０００１】
【発明の属する技術分野】
本発明は、各色毎の現像器を備えた複数の感光体を中間転写体に配置したタンデム式カラー画像形成装置を備えた電子写真複写機、プリンタ、ファクシミリ、これらの複合機等に用いる中間転写体、及びその中間転写体の製造方法に関する。
【０００２】
【従来の技術】
電子写真方式を応用した画像形成装置は、無機又は有機光導電性感光体からなる潜像担持体上に一様な電荷を形成し、画像信号を変調したレーザーや発光ダイオード光等で静電潜像を形成した後、帯電したトナーで前記静電潜像を現像して可視化したトナー像とする。そして、上記トナー像を中間転写体を介して、あるいは直接記録紙等の転写材に静電的に転写することにより所要の再生画像を得る。特に、上記像担持体に形成したトナー像を中間転写体に一次転写し、さらに中間転写体のトナー像を記録紙に二次転写する中間転写方式が知られている。
【０００３】
前記中間転写方式を用いた画像形成装置に用いられる無端ベルトの材料としてはポリカーボネート樹脂（ＰＣ）、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリアルキレンフタレート、ＰＣ／ポリアルキレンフタレート（ＰＡＴ）のブレンド材料、エチレンテトラフルオロエチレン共重合体（ＥＴＦＥ）等の熱可塑性樹脂からなる半導電性の無端ベルト等が提案されている。
【０００４】
また、特許２５６０７２７号、特開平５−７７２５２号公報等において、通常のカーボンブラックを導電性微粉末としてポリイミド樹脂に分散させた中間転写体が提案されている。
【０００５】
【発明が解決しようとする課題】
一方、このような中間転写体を用いる新規な画像形成装置(図１)として、各色毎の現像器１５を備えた複数の感光体９を中間転写体１６に配置し、各色毎に感光体上の顕画像を中間転写体１６上に１サイクルで転写した後、一括して紙等の被転写体へ転写するタンデム式中間転写方式のカラー画像形成装置等が検討されている。
【０００６】
従来より紙等の被転写紙に顕画像を転写する方式として、転写ドラム上に紙等の被転写紙を巻き付け、感光体上の顕画像を各色毎に被転写紙に転写する転写ドラム方式等が知られている。前記転写方式は、タンデム式中間転写方式に比べ、感光体から中間転写体への顕画像の転写が、中間転写体が複数回回転する必要が有ったが、タンデム式中間転写方式は中間転写体が１回転する事で複数の感光体から転写でき転写速度の向上が実現でき、また転写ドラム方式のように被転写体を選ばないというメリットから、今後の有望な転写方式として検討されている。
【０００７】
しかしながら、この転写方式における中間転写体は、従来の中間転写ベルトに比べその径が大きく、独立した４色の現像器と感光体を備えるため、各色毎の色ズレの精度等の高精度な装置設計が必要となる。つまり、このような画像形成装置に搭載される中間転写体としては、高い精度の平面度が要求される。平面度が悪いと、ベルト駆動を行う駆動ロール１１と中間転写体との密着性が変化し、結果的にベルトの移動速度が変動し、各色現像器を具備した感光体に対し中間転写体の移動速度が各色で異なってしまい、高精度の画像合わせが不可能となり、色ずれ等の画像欠陥が発生する。また、画像形成装置の小型化に伴い、近年の画像形成装置の内部は部品同士が近接しており、中間転写体の平面度が悪く、浮き等があると他の部品に接近し放電を起こし画像が抜ける欠陥や近傍の他の部材と接触して中間転写体の端部にダメージを受けたり、最悪の場合引っ掛かり中間転写体が破断したりする等の不都合が生じる。
【０００８】
上記タンデム式カラー画像形成装置に用いる中間転写体としては、上記従来技術における熱可塑性樹脂における中間転写体では、抵抗値のバラツキや厚み精度、表面精度、及び平面度等の点で不充分であった。また、特許２５６０７２７号、特開平５−７７２５２号公報においては、抵抗値の面内バラツキ等に関しては多少の改善が見られたが、該装置に要求される表面精度及び平面度に関しては不充分であった。
【０００９】
本発明は、前記従来技術における諸問題を解決し、以下の目的を達成することを課題とする。即ち、
本発明の目的は、タンデム式中間転写型画像形成装置に用いられる中間転写体において、高精度の平面度、を有し、これにより高品質の転写画像を得ることができる中間転写体及びその製造方法を提供することにある。本発明の更に別の目的は、均一な電気抵抗を有し、かつ、高精度の表面精度、厚み精度を有する中間転写体とその製造方法を提供することにある。
【００１０】
【課題を解決するための手段】
上記課題は、以下の手段により解決される。即ち、本発明は、
【００１１】
＜１＞各色毎の現像器を備えた複数の像担持体を中間転写体に配置したタンデム式カラー画像形成装置に用いられる無端ベルト状の、酸化処理カーボンブラックを含有し且つビフェニル構造を有するポリイミド樹脂製の中間転写体において、前記中間転写体の製造工程の１工程であるポリアミド酸をイミド転化する加熱工程が、０．５時間以上の間、２２０〜２８０℃の加熱温度で保持する加熱条件を包含し、かつ前記中間転写体を２本の平行な軸で４ｋｇの荷重をかけることによって張架した時の平面度が５ｍｍ以下であることを特徴とする中間転写体である。
＜２＞前記加熱条件が、前記加熱温度まで２℃／分の昇温速度で昇温する条件を含む＜１＞に記載の中間転写体である。
【００１２】
＜３＞＜１＞又は＜２＞に記載の中間転写体において、その表面粗度（Ｒａ）が１．５μｍ以下であることを特徴とする中間転写体である。
【００１３】
＜４＞＜１＞から＜３＞のいずれかに記載の中間転写体の製造方法であって、ポリアミド酸溶液を円筒状金型内面に供給・展開して被膜とし、加熱によりベルトとして保持できるまで硬化させた後、金型からベルトを取り出して金属製シリンダ外面に差し替え、加熱によりイミド転化反応を行う工程を含み、該イミド転化反応を行う工程が、加熱温度２２０〜２８０℃、加熱時間０．５時間以上持する工程を含むことを特徴とする中間転写体の製造方法である。
【００１４】
＜５＞＜１＞から＜３＞のいずれかに記載の中間転写体の製造方法であって、ポリアミド酸溶液を円筒状金型内面に供給・展開して被膜とし、加熱によりベルトとして保持できるまで硬化させた後、金型からベルトを取り出して金属製シリンダ外面に差し替え、加熱によりイミド転化反応を行う工程を含み、前記金属製シリンダ外面の表面粗度（Ｒａ）が１．２〜２．０μｍであることを特徴とする中間転写体の製造方法である。
【００１５】
【発明の実施の形態】
本発明の中間転写体はポリイミド樹脂を主成分とする。ポリイミド樹脂は、高ヤング率材料であることから、駆動時（支持ロール、クリーニングブレード等の応力）による変形が少ないので、色ズレ等の画像欠陥が生じにくい中間転写体となる。ポリイミド樹脂は、通常、略等モルのテトラカルボン酸二無水物或いはその誘導体と、ジアミンとを溶媒中で重合反応させてポリアミド酸溶液として得られる。テトラカルボン酸二無水物としては、例えば、下記の一般式（Ｉ）で示されるものが挙げられる。
【００１６】
【化１】

（一般式（Ｉ）中、Ｒは４価の有機基であり、芳香族、脂肪族、環状脂肪族、芳香族と脂肪族を組み合わせたもの、またはそれらの置換された基である。）
【００１７】
テトラカルボン酸二無水物として具体的には、ピロメリット酸二無水物、３，３’，４，４’-ベンゾフェノンテトラカルボン酸二無水物、３，３’，４，４’-ビフェニルテトラカルボン酸二無水物、２，３，３’，４-ビフェニルテトラカルボン酸二無水物、２，３，６，７-ナフタレンテトラカルボン酸二無水物、１，２，５，６-ナフタレンテトラカルボン酸二無水物、１，４，５，８-ナフタレンテトラカルボン酸二無水物、２，２’−ビス（３，４−ジカルボキシフェニル）スルホン酸二無水物、ペリレン−３，４，９，１０−テトラカルボン酸二無水物、ビス（３，４−ジカルボキシフェニル）エーテル二無水物、エチレンテトラカルボン酸二無水物等が挙げられる。
【００１８】
一方、ジアミンの具体例としては、４，４’-ジアミノジフェニルエーテル、４，４’-ジアミノジフェニルメタン、３，３’-ジアミノジフェニルメタン、３，３’-ジクロロベンジジン、４，４’-ジアミノジフェニルスルフィド、３，３’-ジアミノジフェニルスルフォン、１，５-ジアミノナフタレン、m-フェニレンジアミン、p-フェニレンジアミン、３，３’-ジメチル４，４’-ビフェニルジアミン、ベンジジン、３，３’-ジメチルベンジジン、３，３’-ジメトキシベンジジン、４，４’-ジアミノジフェニルスルフォン、４，４’-ジアミノジフェニルプロパン、２，４−ビス（β−アミノ第三ブチル）トルエン、ビス（ｐ−β−アミノ−第三ブチルフェニル）エーテル、ビス（ｐ−β−メチル−δ−アミノフェニル）ベンゼン、ビス−ｐ−（１，１−ジメチル−５−アミノ−ベンチル）ベンゼン、１−イソプロピル−２，４−ｍ−フェニレンジアミン、ｍ−キシリレンジアミン、ｐ−キシリレンジアミン、ジ（ｐ−アミノシクロヘキシル）メタン、ヘキサメチレンジアミン、ヘプタメチレンジアミン、オクタメチレンジアミン、ノナメチレンジアミン、デカメチレンジアミン、ジアミノプロピルテトラメチレン、３−メチルヘプタメチレンジアミン、４，４−ジメチルヘプタメチレンジアミン、２，１１−ジアミノドデカン、１，２−ビス−３−アミノプロボキシエタン、２，２−ジメチルプロピレンジアミン、３−メトキシヘキサメチレンジアミン、２，５−ジメチルヘプタメチレンジアミン、３−メチルヘプタメチレンジアミン、５−メチルノナメチレンジアミン、２，１７−ジアミノエイコサデカン、１，４−ジアミノシクロヘキサン、１，１０−ジアミノ−１，１０−ジメチルデカン、１２−ジアミノオクタデカン、２，２−ビス〔４−（４−アミノフェノキシ）フェニル〕プロパン、ピペラジン、Ｈ₂Ｎ（ＣＨ₂）₃Ｏ（ＣＨ₂）₂Ｏ（ＣＨ₂）ＮＨ₂、Ｈ₂Ｎ（ＣＨ₂）₃Ｓ（ＣＨ₂）₃ＮＨ₂、Ｈ₂Ｎ（ＣＨ₂）₃Ｎ（ＣＨ₃）₂（ＣＨ₂）₃ＮＨ₂等が挙げられる。
【００１９】
テトラカルボン酸二無水物とジアミンを重合反応させる際の溶媒としては、溶解性等の点より極性溶媒が好適に挙げられる。極性溶媒としては、Ｎ，Ｎ−ジアルキルアミド類が好ましく、具体的には、例えば、これの低分子量のものであるＮ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジエチルホルムアミド、Ｎ，Ｎ−ジエチルアセトアミド、Ｎ，Ｎ−ジメチルメトキシアセトアミド、ジメチルスルホキシド、ヘキサメチルホスホルトリアミド、Ｎ−メチル−２−ピロリドン、ピリジン、テトラメチレンスルホン、ジメチルテトラメチレンスルホン等が挙げられる。これらは単数または複数併用することができる。
【００２０】
本発明の中間転写体は、ポリイミド樹脂中に酸化処理カーボンブラックを含有している。酸化処理カーボンブラックは、カーボンブラックを酸化処理することで、表面に酸素含有官能基（例えば、カルボキシル基、キノン基、ラクトン基、水酸基等）を付与して得ることができるものである。この酸化処理は、高温雰囲気下で、空気と接触、反応させる空気酸化法、常温下で窒素酸化物やオゾン等と反応させる方法、及び高温下での空気酸化後、低温下でオゾン酸化する方法等により行うことができる。酸化処理カーボンブラックとして、具体的には、三菱化学製のＭＡ１００(ｐＨ３．５、揮発分１．５％)、同，ＭＡ１００Ｒ（ｐＨ３．５、揮発分１．５％）、同ＭＡ１００Ｓ（ｐＨ３．５、揮発分１．５％）、同＃９７０（ｐＨ３．５、揮発分３．０％）、同ＭＡ１１（ｐＨ３．５、揮発分２．０％）、同＃１０００（ｐＨ３．５、揮発分３．０％）、同＃２２００（ｐＨ３．５，揮発分３．５％）、同ＭＡ２３０（ｐＨ３．０、揮発分１．５％）、同ＭＡ２２０（ｐＨ３．０、揮発分１．０％）、同＃２６５０（ｐＨ３．０、揮発分８．０％）、同ＭＡ７（ｐＨ３．０、揮発分３．０％）、同ＭＡ８（ｐＨ３．０、揮発分３．０％）、同ＯＩＬ７Ｂ(ｐＨ３．０、揮発分６．０％)、同ＭＡ７７（ｐＨ２．５、揮発分３．０％）、同＃２３５０(ｐＨ２．５、揮発分７．５％)、同＃２７００（ｐＨ２．５、揮発分１０．０％）、同＃２４００（ｐＨ２．５、揮発分９．０％）、デグサ社製のプリンテックス１５０Ｔ（ｐＨ４．５、揮発分１０．０％）、同スペシャルブラック３５０（ｐＨ３．５、揮発分２．２％）、同スペシャルブラック１００（ｐＨ３．３、揮発分２．２％）、同スペシャルブラック２５０（ｐＨ３．１、揮発分２．０％）、同スペシャルブラック５（ｐＨ３．０、揮発分１５．０％）、同スペシャルブラック４（ｐＨ３．０、揮発分１４．０％）、同スペシャルブラック４A（ｐＨ３．０、揮発分１４．０％）、同スペシャルブラック５５０（ｐＨ２．８、揮発分２．５％）、同スペシャルブラック６（ｐＨ２．５、揮発分１８．０％）、同カラーブラックＦＷ２００（ｐＨ２．５、揮発分２０．０％）、同カラーブラックＦＷ２（ｐＨ２．５、揮発分１６．５％）、同カラーブラックＦＷ２Ｖ（ｐＨ２．５、揮発分１６．５％）、キャボット社製ＭＯＮＡＲＣＨ１０００（ｐＨ２．５、揮発分９．５％）、キャボット社製ＭＯＮＡＲＣＨ１３００（ｐＨ２．５、揮発分９．５％）、キャボット社製ＭＯＮＡＲＣＨ１４００（ｐＨ２．５、揮発分９．０％）、同ＭＯＧＵＬ-Ｌ（ｐＨ２．５、揮発分５．０％）、同ＲＥＧＡＬ４００Ｒ（ｐＨ４．０、揮発分３．５％）；等が挙げられる。
【００２１】
このようにして得られる酸化処理カーボンブラックは、一部に過剰な電流が流れ、繰返しの電圧印加による酸化の影響を受けにくく、さらに、その表面に付着する酸素含有官能基の効果で、ポリイミド中への分散性が高く、抵抗バラツキを小さくすることができるとともに、電界依存性も小さくなり、転写電圧による電界集中が起き難くなる。その結果、転写電圧による抵抗低下を防止し、電気抵抗の均一性を改善し、電界依存性が少なく、さらに環境による抵抗の変化の少ない、用紙走行部が白く抜けること等の画質欠陥の発生が抑制された高画質を得ることができる中間転写体となる。もし少なくとも２種類含有させる場合、これら酸化処理カーボンブラックは実質的に互いに導電性の異なるものであると好ましく、例えば酸化処理の度合い、ＤＢＰ吸油量、窒素吸着を利用したＢＥＴ法による比表面積等の物性が異なるものを用いる。このように物性の異なる２種類以上のカーボンブラックを添加する場合、例えば高い導電性を発現するカーボンブラックを優先的に添加した後、導電率の低いカーボンブラックを添加して表面抵抗率を調整すること等が可能である。酸化処理カーボンブラックとして具体的には、ＳＰＥＣＩＡＬＢＬＡＣＫ４（デグサ社製、ｐＨ３．０、揮発分：１４．０％）、ＳＰＥＣＩＡＬＢＬＡＣＫ２５０（デグサ社製、ｐＨ３．１、揮発分：２．０％）等が挙げられる。これら酸化処理カーボンブラックの含有量は、ポリイミド樹脂に対して１０〜５０重量％程度が好ましく、より好ましくは１２〜３０重量％である。この含有量が１０重量％未満であると、電気抵抗の均一性が低下し、耐久使用時の表面抵抗率の低下が大きくなる場合があり、一方、５０重量％を超えると、所望の抵抗値が得られ難く、また、成型物として脆くなるため好ましくない。
【００２２】
本発明の酸化処理カーボンブラックを分散したポリイミド樹脂製の中間転写体は、酸化処理カーボンブラックを分散させたポリアミド酸溶液を作製する工程、円筒状金型内面に膜（層）形成する工程、イミド転化を行う工程を経ることで得ることができる。
【００２３】
もし２種類以上の酸化処理カーボンブラックを分散させたポリアミド酸溶液の製造方法については、溶媒中に２種類以上の酸化処理カーボンブラックを予め分散した分散液中に上記酸二無水物成分及びジアミン成分を溶解・重合する方法、２種類以上の酸化処理カーボンブラックを各々溶媒中に分散させ２種類以上のカーボンブラック分散液を作製し、この分散液に酸無水物成分及びジアミン成分を溶解・重合させた後、各々のポリアミド酸溶液を混合する方法等が考えられ、適宜選択してカーボンブラックを分散したポリアミド酸溶液を作製する。
【００２４】
本発明の中間転写体は、このようにして得られたポリアミド酸溶液を円筒状金型内面に供給・展開して被膜とし、加熱によりポリアミド酸をイミド転化させることにより得られる。本発明ではこのイミド転化させる加熱工程において、０．５時間以上の間、一定の温度で保持する加熱条件で、イミド転化を行うことにより、平面度が良好な中間転写体を得ることができる。以下詳細に説明する。
【００２５】
本発明では、前記ポリアミド酸溶液を円筒状金型内面に供給する。この供給方法は、ディスペンサーによる方法、ダイスによる方法等適宜選択して行うことができる。この時用いる円筒金型の内周面の表面状態は、本発明では鏡面仕上げしたものが好ましい。このようにして供給したポリアミド酸溶液を、加熱しながら遠心成形する方法、弾丸状走行体を用いて成形する方法、回転成形する方法等適宜選択して均一な膜厚の被膜を形成する。続いて内周面に被膜を形成した金型ごと乾燥機中で加温して、イミド転化まで昇温する方法、もしくはベルトとして形状を保持できるまで溶媒の除去を行った後、金型内面から剥離し金属製シリンダ外面に差し替えた後、該シリンダごと加熱してイミド転化を行う方法等が考えられる。好適な平面度及び外表面精度の中間転写体を得るためには、ベルトとして保持できるまで溶媒の除去を行った後、金属製シリンダに差し替えてイミド転化を行う方法が好ましい。この溶媒を除去する工程における加熱条件は、溶媒の除去が進行する条件であれば、特に制限されないが、好ましくは８０〜２００℃で０．５〜５時間である。次いでベルトとしてそれ自身形状を保持することができるようになった成形物を金型内周面から剥離する。この時、金型内周面に離型処理を施すこともできる。
【００２６】
次いで、ベルト形状として保持できるまで加熱・硬化させた成形物を、金属製シリンダ外面に差し替え、差し替えたシリンダごと加熱することにより、ポリアミド酸のイミド転化反応を進行させる。この時用いる金属製シリンダは、線膨張係数がポリイミド樹脂よりも大きいものが好ましく、シリンダの外径をポリイミド成形物の内径より所定量小さくすることで、ヒートセットを行うことができ均一な膜厚でムラのない無端ベルトを得ることができる。この時用いる金属製シリンダ外面の表面粗度（Ｒａ）は、１．２〜２．０μｍであると好ましい。金属製シリンダ外面の表面粗度（Ｒａ）が１．２μｍより小さいと、金属製シリンダ自身が平滑過ぎるために得られるベルト状中間転写体がベルトの軸方向に対する収縮による滑りが発生しないため、延伸がこの工程で行われ、これにより膜厚のバラツキや平面度の精度の低下が発生する。また、金属製シリンダ外面の表面粗度（Ｒａ）が２．０μｍより大きいと金属製シリンダ外面がベルト状中間転写体の内面に転写し、さらには外面に凹凸を発生させ、これにより画像不良を発生させる。このようにして得られたカーボンブラックを分散させたポリイミド樹脂から成るベルト状の中間転写体の外面の表面粗さ（Ｒａ）は、１．５μｍ以下である。本発明における表面粗度はＪＩＳＢ６０１に準じ測定したものである。中間転写体の表面粗度（Ｒａ）が１．５μｍより大きいとがさつき等の画像欠陥が発生する。この理由としては局部的に転写の際に印加する電圧や剥離放電による電界が、ベルト表面の凸部に集中することにより、この部分の表面が変質して、新しい導電経路ができて抵抗が低下し濃度低下が起き、画像全体ではがさついているように見えると考えられる。
【００２７】
また、本発明ではイミド転化を行う加熱工程の条件が、加熱温度が２２０〜２８０℃、加熱時間０．５〜２時間であると好ましい。ポリイミド樹脂の組成にもよるが、イミド転化の際の加熱条件でこの領域において、最も収縮量が大きくなるため、ベルトの軸方向についての収縮を緩やかに行うことにより、膜厚バラツキや平面度の精度の低下を防ぐことができる。このような加熱工程を経た中間転写体は、その平面度が５ｍｍ以下となるが、好ましくは、３ｍｍ以下が望ましい。平面度が５ｍｍ以下ではガサツキがなく、色ずれも少ない。しかしベルト端部が上下にハネている場合５ｍｍ以下でも中間転写体を使用中に破断する事はないが、周辺部材に接触したあとが残ることが希にある。更に、平面度が３ｍｍ以下になると中間転写体を使用中に周辺部材に接触する事もなく色ずれもほとんどなくなる。
【００２８】
本発明における平面度は、図２に示すように中間転写体を２本の平行な軸１８（Φ２８ｍｍ）で４ｋｇの荷重をかけることにより張架し、その時の中間転写体表面をレーザー変位計１７（キーエンス社製ＬＫ−０３０）で張架している軸と対になっている軸の中心から２００ｍｍの位置を軸に平行に前記レーザー変位計１７でベルト表面の変位量の最大値と最小値の差分を読み取ったものである。
【００２９】
本発明の中間転写体は、ベルト形状で、特にシームレスベルト（無端ベルト）であると好ましい。このシームレスベルトの場合、ベルトの厚さはその使用目的に応じて適宜決定しうるが、一般的には強度や柔軟性等の機械的特性より、２０〜５００μｍ程度が好ましく、特に好ましくは５０〜２００μｍである。
【００３０】
このような中間転写体は、平面度が良好であるため、タンデム式画像形成装置に好適に用いることができる。タンデム式画像形成装置は、従来から知られている転写ドラム方式や中間転写方式のように、各色毎に潜像形成・現像・転写・除電・クリーニングを繰り返すことがなく、複数の像担持体が配置したものであるため、格段に画像形成速度が向上するというメリットがある。この時、本発明の中間転写体を用いると、その平面度、表面粗度、及び厚み精度が良好であるため、良好な画像を得ることができる。
【００３１】
（画像形成装置）
本発明の画像形成装置は、前記本発明の中間転写体を備え、例えば、４色（ブラック、イエロー、マゼンタ、シアン）の現像器１５を備えた各色毎の感光体９が中間転写体１６に配置したタンデム式カラー画像形成装置に適用できる。前記本発明の中間転写体を備えることで、高画質の転写画像を得ることができる。具体的には、感光体９表面を均一に帯電する帯電ロール１３（帯電装置）、感光体９表面を露光し静電潜像を形成するレーザー発生装置８ (露光装置)、感光体９表面に形成された潜像を現像剤を用いて現像し、トナー像を形成する現像器１５ (現像装置)、感光体に付着したトナーやゴミ等を除去する感光体クリナー１４ (クリーニング装置)、被転写材上のトナー像を定着する定着する定着ロール２等必要に応じて公知の方法で任意に備えることができる。
【００３２】
像担持体としては、従来公知のものを用いることができ、その感光層としては、有機系、アモルファスシリコン等公知のものを用いることができる。前期像担持体が円筒状の場合は、アルミニウム又はアルミニウム合金を押出し成型後、表面加工する等の公知の製法により得られる。またベルト状の前記像担持体を用いることも可能である。
【００３３】
帯電手段としては、特に制限はなく、例えば、導電性又は半導電性のローラ、ブラシ、フィルム、ゴムブレード等を用いた接触型帯電器、コロナ放電を利用したスコロトロン帯電器やコロトロン帯電器などのそれ自体公知の帯電器が挙げられる。これらの中でも、帯電補償能力に優れる点で接触型帯電器が好ましい。前記帯電手段は、前記電子写真感光体に対し、通常、直流電流を印加するが、交流電流をさらに重畳させて印加してもよい。
【００３４】
露光手段としては、特に制限はなく、例えば、前記電子写真感光体表面に、半導体レーザ光、ＬＥＤ光、液晶シャッタ光等の光源、或いはこれらの光源からポリゴンミラーを介して所望の像様に露光できる光学系機器等が挙げられる。
【００３５】
現像手段としては、目的に応じて適宜選択することができるが、例えば、一成分系現像剤又は二成分系現像剤をブラシ、ローラ等を用い接触或いは非接触させて現像する公知の現像器等が挙げられる。
【００３６】
第一転写手段としては、例えば、ベルト、ローラ、フィルム、ゴムブレード等を用いた接触型転写帯電器、コロナ放電を利用したスコロトロン転写帯電器やコロトロン転写帯電器等のそれ自体公知の転写帯電器が挙げられる。これらの中でも、転写帯電補償能力に優れる点で接触型転写帯電器が好ましい。なお、本発明においては、前記転写帯電器の他、剥離帯電器等を併用することもできる。
【００３７】
第二転写手段としては、前記第一転写手段として例示した転写ローラ等の接触型転写帯電器、スコロトロン転写帯電器やコロトロン転写帯電器等が挙げられる。これらの中でも、前記第一転写手段と同様に接触型転写帯電器が好ましい。転写ローラ等の接触型転写帯電器により強く押圧するようにすると、画像の転写状態を良好な状態に維持させることができる。また、中間転写体を案内するローラの位置で転写ローラ等の接触型転写帯電器を押圧すると、中間転写体から被転写体に対してトナー像を移転させる作用を良好な状態で行うことが可能になる。
【００３８】
光除電手段としては、例えば、タングステンランプ、ＬＥＤ等が挙げられ、該光除電プロセスに用いる光質としては、例えば、タングステンランプ等の白色光、ＬＥＤ光等の赤色光等が挙げられる。該光除電プロセスにおける照射光強度としては、通常、電子写真感光体の半減露光感度を示す光量の数倍乃至３０倍程度になるよう出力設定される。
【００３９】
クリーニング手段としては、特に制限はなく、それ自体公知のクリーニング装置等を用いればよい。
定着手段としては、特に制限はなく、それ自体公知の定着器、例えば熱ローラ定着器、オーブン定着器等が挙げられる。
【００４０】
【実施例】
以下、本発明を、実施例を挙げてさらに具体的に説明する。ただし、これら各実施例は、本発明を制限するものではない。
【００４１】
＜実施例１＞
酸化処理カーボンブラック入り(デグサ社製スペシャルブラック４)３、３’、４、４’−ビフェニルテトラカルボン酸(ＢＰＤＡ)とｐ−フェニレンジアミン（ＰＤＡ）からなるポリアミド酸ＮＭＰ溶液を円筒状金型内面に、ディスペンサーを介して４００μｍに塗布し、１５００ｒｐｍで（１５分間）回転させて均一な厚みを有する展開層とした後、（２５０ｒｐｍ）で回転させながら、金型の外側より６０℃の熱風を３０分間あて、次いで１５０℃で６０分間加熱した後室温に戻し成形した。この後、金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度(Ｒａ)が１．８μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２５０℃で１時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。その後室温に戻し、目的とする中間転写ベルトを得た。このベルトの厚さは７５μｍであった。この中間転写ベルトを用い、画像は図１に示す、４色（ブラック、イエロー、マゼンタ、シアン）の現像器１５中にポリエステル系ＤｏｃｕＰｒｉｎｔＣ６２０用トナーを備えた各色毎のトリフェニルアミンを主な電荷輸送剤としポリカーボネートに分散した電荷輸送層とフタロシアニン系の電荷発生層を有する感光体９が中間転写体１６に配置したタンデム式カラー画像形成装置にて画像欠陥の評価を行った。平面度は、中間転写体を２本の平行な軸（Φ２８）で４ｋｇの荷重で張架した時の中間転写体表面をレーザー変位計（キーエンス社製ＬＫ−０３０）で軸の中心から２００ｍｍの位置を軸に平行に前記レーザー変位計でベルト表面の変位量の最大値と最小値の差分を読み取った。アルミ製シリンダーと中間転写体ベルトの表面粗度はＪＩＳＢ６０１に準じ測定したものである。その結果得られた中間転写ベルトの表面粗度は１．４μｍで平面度１．２ｍｍで画像評価を行った所、ガサツキ、色ずれなど無く良好な画像が得られた。
【００４２】
＜実施例２＞
前記実施例１に対し酸化処理カーボンブラックを２種混合し(デグサ社製スペシャルブラック４とデグサ社製スペシャルブラック２５０)を用い、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が１．４μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２８０℃で０．５時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．２μｍで平面度２．９ｍｍで画像評価を行った所、ガサツキ、色ずれなど無く良好な画像が得られた。
【００４３】
＜実施例３＞
前記実施例１に対し酸化処理カーボンブラックを２種混合し(デグサ社製スペシャルブラック４とデグサ社製スペシャルブラック２５０)を用い、３、３’、４、４’−ビフェニルテトラカルボン酸(ＢＰＤＡ)とｐ−フェニレンジアミン（ＰＤＡ）からなるポリアミド酸ＮＭＰ溶液と３、３’、４、４’−ビフェニルテトラカルボン酸(ＢＰＤＡ)とオキシジアニリン（ＯＤＡ）からなるポリアミド酸ＮＭＰ溶液を８：２で混合し、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が１．２μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２２０℃で０．５時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は０．９μｍで平面度４．２ｍｍで画像評価を行った所、ガサツキは、無く、色ずれは若干認められるが問題ないレベルだった。
【００４４】
＜実施例４＞
前記実施例１に対し酸化処理カーボンブラックを(デグサ社製スペシャルブラック４)を用い、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が２．０μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２５０℃で３．０時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．５μｍで平面度１．２ｍｍで画像評価を行った所、ガサツキ、色ずれなど無く良好な画像が得られた。
【００４５】
＜実施例５＞
前記実施例１に対し酸化処理カーボンブラックを２種混合し(デグサ社製スペシャルブラック４とデグサ社製スペシャルブラック２５０)を用い、３、３’、４、４’−ビフェニルテトラカルボン酸(ＢＰＤＡ)とｐ−フェニレンジアミン（ＰＤＡ）からなるポリアミド酸ＮＭＰ溶液と３、３’、４、４’−ビフェニルリテトラカルボン酸(ＢＰＤＡ)とオキシジアニリン（ＯＤＡ）からなるポリアミド酸ＮＭＰ溶液を８：２で混合し、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が１．５μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２２０℃で０．７時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．３μｍで平面度３．８ｍｍで画像評価を行った所、ガサツキは、無く、色ずれは若干認められるが問題ないレベルだった。
【００４６】
＜実施例６＞
前記実施例１に対し酸化処理カーボンブラックを(デグサ社製スペシャルブラック４)を用い、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が２．０μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２５０℃で１．０時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．７μｍで平面度１．２ｍｍで画像評価を行った所、ガサツキは発生したが、色ずれは無い画像だった。
【００４７】
＜実施例７＞
前記実施例１に対し酸化処理カーボンブラックを２種混合し(デグサ社製スペシャルブラック４とデグサ社製スペシャルブラック２５０)を用い、３、３’、４、４’−ビフェニルテトラカルボン酸(ＢＰＤＡ)とｐ−フェニレンジアミン（ＰＤＡ）からなるポリアミド酸ＮＭＰ溶液と３、３’、４、４’−ビフェニルリテトラカルボン酸(ＢＰＤＡ)とオキシジアニリン（ＯＤＡ）からなるポリアミド酸ＮＭＰ溶液を８：２で混合し、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が２．５μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２２０℃で０．７時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．８μｍで平面度４．０ｍｍで画像評価を行った所、ガサツキは、非常に悪く、色ずれは若干認められるが問題にならないレベルだった。但し、中間転写体使用後、端部に若干他の近傍部材に接触した跡が発見できた。
【００４８】
【比較例】
＜比較例１＞
前記実施例１に対し酸化処理カーボンブラックを(デグサ社製スペシャルブラック４)を用い、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が１．８μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２３０℃で０．４時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．４μｍで平面度５．３ｍｍで画像評価を行った所、ガサツキは無いが、色ずれが目視上明確にわかる画像だった。
【００４９】
＜比較例２＞
前記実施例１に対し酸化処理カーボンブラックを２種混合し(デグサ社製スペシャルブラック４とデグサ社製スペシャルブラック２５０)を用い、３、３’、４、４’−ビフェニルテトラカルボン酸(ＢＰＤＡ)とｐ−フェニレンジアミン（ＰＤＡ）からなるポリアミド酸ＮＭＰ溶液と３、３’、４、４’−ビフェニルリテトラカルボン酸(ＢＰＤＡ)とオキシジアニリン（ＯＤＡ）からなるポリアミド酸ＮＭＰ溶液を８：２で混合し、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が１．２μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２５０℃で０．２時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は０．９μｍで平面度６．０ｍｍで画像評価を行った所、ガサツキは、無いが、色ずれは目視上明確にわかりかつ中間転写ベルトが他の部材に接触し放電が発生し画像抜けも発生した。
【００５０】
＜比較例３＞
前記実施例１に対し酸化処理カーボンブラックを(デグサ社製スペシャルブラック４)を用い、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が２．０μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２００℃で０．５時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は１．５μｍで平面度５．５ｍｍで画像評価を行った所、ガサツキは無いが、色ずれが目視上明確にわかる画像だった。又、中間転写体端部は、近傍部材に接触し著しくダメージを受けていた。
【００５１】
＜比較例４＞
前記実施例１に対し酸化処理カーボンブラックを２種混合し(デグサ社製スペシャルブラック４とデグサ社製スペシャルブラック２５０)を用い、成形後金型内面から自己支持できるまで硬化したポリアミド酸ベルトを剥離し、表面粗度（Ｒａ）が１．１μｍのアルミ製シリンダーの外面に差し替えた後、２５０℃まで２℃／分の昇温速度で昇温し、２８０℃で０．２時間保持した後、更に３００℃まで２℃／分の昇温速度で３０分加熱し、イミド転化反応の完結を行った。他の条件は実施例１と同様に中間転写体ベルトを作成しタンデム式カラー画像形成装置にて画像評価を行い、表面粗度と平面度を測定した。その結果得られた中間転写ベルトの表面粗度は０．７μｍで平面度６．７ｍｍで画像評価を行った所、ガサツキが発生し、色ずれは目視上明確にわかりかつ中間転写ベルトが他の部材に接触し放電が発生し画像抜けも発生した。
【００５２】
【発明の効果】
以上により、本発明によれば、タンデム式中間転写型画像形成装置に用いられる中間転写体において、高精度の平面度、を有し、これにより高品質の転写画像を得ることができる中間転写体及びその製造方法を提供できる。
また、本発明によれば、均一な電気抵抗を有し、かつ、高精度の表面精度、厚み精度を有する中間転写体とその製造方法を提供することができる。
【図面の簡単な説明】
【図１】画像形成装置の概略図である。
【図２】平面度を測定するための測定装置の概略図である。
【符号の説明】
１トナーカートリッジ
２定着ロール
３バックアップロール
４テンションロール
５２次転写ロール
６用紙経路
７用紙トレイ
８レーザー発生装置
９感光体
１０１次転写ロール
１１駆動ロール
１２転写クリナー
１３帯電ロール
１４感光体クリナー
１５現像器
１６中間転写体
１７レーザー変位計
１８平面度計ベルト張架軸[0001]
BACKGROUND OF THE INVENTION
The present invention provides an intermediate transfer for use in an electrophotographic copying machine, a printer, a facsimile, a composite machine, or the like having a tandem type color image forming apparatus in which a plurality of photosensitive members each having a developing device for each color are arranged on an intermediate transfer member. And a method for producing the intermediate transfer member.
[0002]
[Prior art]
An image forming apparatus using an electrophotographic system forms a uniform charge on a latent image carrier made of an inorganic or organic photoconductive photosensitive member, and electrostatic latent images are generated by a laser or light emitting diode light that modulates an image signal. After the image is formed, the electrostatic latent image is developed with charged toner to obtain a visualized toner image. Then, the toner image is electrostatically transferred to a transfer material such as a recording sheet through an intermediate transfer member or a required reproduction image is obtained. In particular, an intermediate transfer system is known in which the toner image formed on the image carrier is primarily transferred to an intermediate transfer member, and the toner image on the intermediate transfer member is secondarily transferred to a recording sheet.
[0003]
Materials for the endless belt used in the image forming apparatus using the intermediate transfer method include polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene phthalate, PC / polyalkylene phthalate (PAT) blend material, ethylene tetra A semiconductive endless belt made of a thermoplastic resin such as fluoroethylene copolymer (ETFE) has been proposed.
[0004]
Japanese Patent No. 2560727, Japanese Patent Application Laid-Open No. 5-77252, etc. propose an intermediate transfer member in which ordinary carbon black is dispersed as a conductive fine powder in a polyimide resin.
[0005]
[Problems to be solved by the invention]
On the other hand, as a new image forming apparatus (FIG. 1) using such an intermediate transfer member, a plurality of photosensitive members 9 each having a developing device 15 for each color are arranged on the intermediate transfer member 16 and the respective photosensitive members are arranged on the photosensitive member. A color image forming apparatus of a tandem type intermediate transfer system, in which the developed image is transferred onto the intermediate transfer body 16 in one cycle and then transferred to a transfer medium such as paper, has been studied.
[0006]
Conventionally, as a method for transferring a visible image onto a transfer paper such as paper, a transfer drum method for winding a transfer paper such as paper on a transfer drum and transferring the visible image on the photosensitive member to the transfer paper for each color, etc. It has been known. Compared with the tandem intermediate transfer method, the transfer method requires transfer of the visible image from the photosensitive member to the intermediate transfer member, but the intermediate transfer member needs to rotate a plurality of times. It is considered as a promising transfer method in the future because it can be transferred from multiple photoconductors by rotating the body once, and the transfer speed can be improved, and the transfer target can be selected like the transfer drum method. .
[0007]
However, the intermediate transfer member in this transfer system has a diameter larger than that of the conventional intermediate transfer belt and is provided with independent four-color developing devices and photoconductors, so that a high-precision device such as the accuracy of color misregistration for each color is provided. Design is required. That is, high accuracy flatness is required as an intermediate transfer member mounted on such an image forming apparatus. If the flatness is poor, the adhesion between the driving roll 11 that drives the belt and the intermediate transfer member changes, and as a result, the moving speed of the belt fluctuates. The moving speed is different for each color, so that high-precision image alignment is impossible, and image defects such as color misregistration occur. As the image forming apparatus is downsized, the parts inside the image forming apparatus in recent years are close to each other, and the flatness of the intermediate transfer member is poor. Inconveniences such as a defect in which an image is lost or contact with another member nearby causes damage to the end of the intermediate transfer member, or in the worst case, the intermediate transfer member is caught and broken.
[0008]
As the intermediate transfer member used in the tandem color image forming apparatus, the intermediate transfer member in the thermoplastic resin in the prior art is not sufficient in terms of variation in resistance value, thickness accuracy, surface accuracy, flatness, and the like. It was. Further, in Japanese Patent No. 2560727 and Japanese Patent Application Laid-Open No. 5-77252, some improvement was observed with respect to the in-plane variation of the resistance value, but the surface accuracy and flatness required for the device were insufficient. there were.
[0009]
An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is,
SUMMARY OF THE INVENTION An object of the present invention is an intermediate transfer member used in a tandem intermediate transfer type image forming apparatus, which has a high degree of flatness and can thereby obtain a high-quality transfer image, and its production. It is to provide a method. Still another object of the present invention is to provide an intermediate transfer member having uniform electric resistance and high surface accuracy and thickness accuracy, and a method for manufacturing the intermediate transfer member.
[0010]
[Means for Solving the Problems]
  The above problem is solved by the following means. That is, the present invention,
[0011]
  <1> An endless belt-like shape used in a tandem color image forming apparatus in which a plurality of image carriers having developing units for respective colors are arranged on an intermediate transfer body,Contains oxidized carbon black andIn the intermediate transfer body made of polyimide resin having a biphenyl structure, the heating step for converting imide to polyamic acid, which is one step of the manufacturing process of the intermediate transfer body, is performed at a heating temperature of 220 to 280 ° C. for 0.5 hour or more. An intermediate transfer member characterized in that the flatness when the intermediate transfer member is stretched by applying a load of 4 kg with two parallel axes is 5 mm or less. is there.
  <2> The intermediate transfer member according to <1>, wherein the heating condition includes a condition of increasing the temperature to the heating temperature at a temperature increase rate of 2 ° C./min.
[0012]
  <3> The intermediate transfer member according to <1> or <2>, wherein the surface roughness (Ra) is 1.5 μm or less..
[0013]
  <4> <1> to <3The method for producing an intermediate transfer member according to any one of the above, wherein the polyamic acid solution is supplied to and spread on the inner surface of the cylindrical mold to form a coating, which is cured until it can be held as a belt by heating. The step of taking out the belt and replacing it with the outer surface of the metal cylinder and performing an imide conversion reaction by heating includes the step of performing the imide conversion reaction by having a heating temperature of 220 to 280 ° C. and a heating time of 0.5 hours or more. This is a method for producing an intermediate transfer member.
[0014]
  <5> <1> to <3The method for producing an intermediate transfer member according to any one of the above, wherein the polyamic acid solution is supplied to and spread on the inner surface of the cylindrical mold to form a coating, which is cured until it can be held as a belt by heating. An intermediate characterized in that it includes a step of taking out the belt and replacing it with a metal cylinder outer surface and performing an imide conversion reaction by heating, wherein the metal cylinder outer surface has a surface roughness (Ra) of 1.2 to 2.0 μm. This is a method for producing a transfer body.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The intermediate transfer member of the present invention contains a polyimide resin as a main component. Since the polyimide resin is a material having a high Young's modulus, it is less likely to be deformed by driving (stress of a support roll, a cleaning blade, etc.), so that it becomes an intermediate transfer body in which image defects such as color misregistration are unlikely to occur. A polyimide resin is usually obtained as a polyamic acid solution by polymerizing a substantially equimolar amount of tetracarboxylic dianhydride or its derivative and a diamine in a solvent. As tetracarboxylic dianhydride, what is shown by the following general formula (I) is mentioned, for example.
[0016]
[Chemical 1]

(In the general formula (I), R is a tetravalent organic group, and is an aromatic, aliphatic, cycloaliphatic, a combination of aromatic and aliphatic, or a substituted group thereof.)
[0017]
Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Acid dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid Dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) sulfonic dianhydride, perylene-3,4,9,10 -Tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride, etc. are mentioned.
[0018]
On the other hand, specific examples of the diamine include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylpropane, 2,4-bis (β-aminotert-butyl) toluene, bis (p-β-amino-tertiary) Tributylphenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1 , 1-dimethyl-5-amino-benzyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine , Heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis -3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,17- The Minoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 12-diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, piperazine, H₂N (CH₂)_ThreeO (CH₂)₂O (CH₂) NH₂, H₂N (CH₂)_ThreeS (CH₂)_ThreeNH₂, H₂N (CH₂)_ThreeN (CH_Three)₂(CH₂)_ThreeNH₂Etc.
[0019]
As the solvent for the polymerization reaction of tetracarboxylic dianhydride and diamine, a polar solvent is preferably used from the viewpoint of solubility. As the polar solvent, N, N-dialkylamides are preferable, and specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, which are low molecular weight compounds thereof. N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone and the like. These can be used singly or in combination.
[0020]
The intermediate transfer member of the present invention contains oxidized carbon black in a polyimide resin. Oxidized carbon black can be obtained by oxidizing carbon black to give an oxygen-containing functional group (for example, carboxyl group, quinone group, lactone group, hydroxyl group, etc.) to the surface. This oxidation treatment is an air oxidation method in which contact is caused to react with air in a high temperature atmosphere, a method in which it reacts with nitrogen oxide or ozone at room temperature, and a method in which ozone oxidation is performed at low temperature after air oxidation at high temperature. Etc. Specifically, as oxidation-treated carbon black, MA100 (pH 3.5, volatile matter 1.5%), MA100R (pH3.5, volatile matter 1.5%), MA100S (pH3. 5, volatiles 1.5%), # 970 (pH 3.5, volatiles 3.0%), MA11 (pH 3.5, volatiles 2.0%), # 1000 (pH 3.5, volatiles) 3.0%), # 2200 (pH 3.5, volatile content 3.5%), MA 230 (pH 3.0, volatile content 1.5%), MA 220 (pH 3.0, volatile content 1.0) %), # 2650 (pH 3.0, volatile matter 8.0%), MA7 (pH 3.0, volatile matter 3.0%), MA8 (pH 3.0, volatile matter 3.0%), OIL7B (pH 3.0, volatile content 6.0%), MA77 (pH 2.5, volatile content 3.0%), # 235 0 (pH 2.5, volatile content 7.5%), # 2700 (pH 2.5, volatile content 10.0%), # 2400 (pH 2.5, volatile content 9.0%), manufactured by Degussa Printex 150T (pH 4.5, volatile content 10.0%), Special Black 350 (pH 3.5, volatile content 2.2%), Special Black 100 (pH 3.3, volatile content 2.2%), Special Black 250 (pH 3.1, volatile content 2.0%), Special Black 5 (pH 3.0, volatile content 15.0%), Special Black 4 (pH 3.0, volatile content 14.0%) Special Black 4A (pH 3.0, volatile content 14.0%), Special Black 550 (pH 2.8, volatile content 2.5%), Special Black 6 (pH 2.5, volatile content 18.0%) ), Same color black FW 00 (pH 2.5, volatile content 20.0%), same color black FW2 (pH 2.5, volatile content 16.5%), same color black FW2V (pH 2.5, volatile content 16.5%), Cabot Corporation MONARCH1000 (pH 2.5, volatile content 9.5%), MONARCH 1300 (pH 2.5, volatile content 9.5%) manufactured by Cabot, MONARCH 1400 (pH 2.5, volatile content 9.0%) manufactured by Cabot, MOGUL-L (pH 2.5, volatile matter 5.0%), REGAL400R (pH 4.0, volatile matter 3.5%);
[0021]
The oxidation-treated carbon black obtained in this way has an excessive current flowing in part, is not easily affected by oxidation due to repeated voltage application, and further has an oxygen-containing functional group adhering to the surface. In addition to being able to reduce dispersion in resistance and electric field dependency, electric field concentration due to transfer voltage is less likely to occur. As a result, resistance degradation due to transfer voltage is prevented, uniformity of electrical resistance is improved, electric field dependency is small, resistance change due to the environment is small, and image quality defects such as whitening of the paper running part occur. The intermediate transfer member can obtain a suppressed high image quality. If at least two types are included, these oxidized carbon blacks preferably have substantially different conductivity, such as the degree of oxidation treatment, DBP oil absorption, specific surface area by the BET method using nitrogen adsorption, etc. Use materials with different physical properties. When two or more types of carbon blacks having different physical properties are added as described above, for example, carbon black exhibiting high conductivity is preferentially added, and then carbon black having low conductivity is added to adjust the surface resistivity. It is possible. Specific examples of the oxidized carbon black include SPECIAL BLACK4 (Degussa, pH 3.0, volatile content: 14.0%), SPECIAL BLACK250 (Degussa, pH 3.1, volatile content: 2.0%), and the like. Is mentioned. The content of the oxidized carbon black is preferably about 10 to 50% by weight, more preferably 12 to 30% by weight, based on the polyimide resin. If this content is less than 10% by weight, the uniformity of electrical resistance may decrease, and the decrease in surface resistivity during durable use may increase. On the other hand, if it exceeds 50% by weight, the desired resistance value may be obtained. Is not preferred, and it is not preferable because it becomes brittle as a molded product.
[0022]
The intermediate transfer member made of a polyimide resin in which the oxidized carbon black of the present invention is dispersed includes a step of preparing a polyamic acid solution in which the oxidized carbon black is dispersed, a step of forming a film (layer) on the inner surface of the cylindrical mold, an imide It can be obtained through a process of converting.
[0023]
If the polyamic acid solution is prepared by dispersing two or more types of oxidized carbon black, the acid dianhydride component and the diamine component are added to a dispersion in which two or more types of oxidized carbon black are previously dispersed in a solvent. Dissolve and polymerize 2 or more types of oxidized carbon black in a solvent to prepare 2 or more types of carbon black dispersion, and dissolve and polymerize acid anhydride component and diamine component in this dispersion Then, a method of mixing each polyamic acid solution, etc. can be considered, and a polyamic acid solution in which carbon black is dispersed is prepared by appropriately selecting.
[0024]
The intermediate transfer member of the present invention can be obtained by supplying and spreading the polyamic acid solution thus obtained on the inner surface of a cylindrical mold to form a film, and converting the polyamic acid to imide by heating. In the present invention, an intermediate transfer member having good flatness can be obtained by performing imide conversion in the heating step for imide conversion under the heating condition of maintaining at a constant temperature for 0.5 hour or more. This will be described in detail below.
[0025]
In the present invention, the polyamic acid solution is supplied to the inner surface of the cylindrical mold. This supply method can be performed by appropriately selecting a method using a dispenser, a method using a die, or the like. The surface state of the inner peripheral surface of the cylindrical mold used at this time is preferably mirror-finished in the present invention. A coating film having a uniform film thickness is formed by appropriately selecting the polyamic acid solution supplied in this manner, such as a method of performing centrifugal molding while heating, a method of molding using a bullet-shaped traveling body, or a method of rotational molding. Subsequently, the mold with the coating film formed on the inner peripheral surface is heated in a dryer and heated until imide conversion, or after removing the solvent until the shape can be maintained as a belt, from the inner surface of the mold A method may be considered in which, after peeling and replacing the outer surface of a metal cylinder, the entire cylinder is heated to perform imide conversion. In order to obtain an intermediate transfer member having suitable flatness and outer surface accuracy, it is preferable to remove the solvent until it can be held as a belt, and then replace it with a metal cylinder to perform imide conversion. The heating conditions in the step of removing the solvent are not particularly limited as long as the removal of the solvent proceeds, but preferably at 80 to 200 ° C. for 0.5 to 5 hours. Next, the molded product that can retain its shape as a belt is peeled off from the inner peripheral surface of the mold. At this time, a mold release process can be performed on the inner peripheral surface of the mold.
[0026]
Next, the molded product heated and cured until it can be held in a belt shape is replaced with the outer surface of the metal cylinder, and the replaced cylinder is heated to advance the imide conversion reaction of the polyamic acid. The metal cylinder used at this time preferably has a linear expansion coefficient larger than that of the polyimide resin. By making the outer diameter of the cylinder smaller than the inner diameter of the polyimide molding by a predetermined amount, heat setting can be performed and a uniform film thickness can be obtained. Thus, an endless belt without unevenness can be obtained. The surface roughness (Ra) of the outer surface of the metal cylinder used at this time is preferably 1.2 to 2.0 μm. If the surface roughness (Ra) of the outer surface of the metal cylinder is smaller than 1.2 μm, the belt-shaped intermediate transfer member obtained because the metal cylinder itself is too smooth will not slip due to contraction in the axial direction of the belt. This is performed in this step, which causes variations in film thickness and a decrease in flatness accuracy. Also, if the surface roughness (Ra) of the outer surface of the metal cylinder is larger than 2.0 μm, the outer surface of the metal cylinder is transferred to the inner surface of the belt-shaped intermediate transfer member, and unevenness is generated on the outer surface, thereby causing image defects. generate. The surface roughness (Ra) of the outer surface of the belt-shaped intermediate transfer member made of polyimide resin in which carbon black thus obtained is dispersed is 1.5 μm or less. The surface roughness in the present invention is measured according to JIS B601. When the surface roughness (Ra) of the intermediate transfer member is larger than 1.5 μm, image defects such as roughening occur. The reason for this is that when the voltage applied locally during transfer or the electric field due to the stripping discharge is concentrated on the convex part of the belt surface, the surface of this part is altered and a new conductive path is created, resulting in a decrease in resistance. However, the density is lowered, and it seems that the entire image looks cluttered.
[0027]
Moreover, in this invention, it is preferable that the conditions of the heating process which performs imide conversion are heating temperature 220-280 degreeC and heating time 0.5-2 hours. Although depending on the composition of the polyimide resin, the amount of shrinkage is the largest in this region under the heating conditions during imide conversion.Thus, by gently performing the shrinkage in the axial direction of the belt, film thickness variation and flatness A reduction in accuracy can be prevented. The intermediate transfer member that has undergone such a heating step has a flatness of 5 mm or less, preferably 3 mm or less. When the flatness is 5 mm or less, there is no roughness and color deviation is small. However, when the belt end portion is bent vertically, the intermediate transfer member will not break during use even if it is 5 mm or less, but it rarely remains after contacting the peripheral member. Further, when the flatness is 3 mm or less, the intermediate transfer member is not brought into contact with the peripheral member during use and there is almost no color shift.
[0028]
As shown in FIG. 2, the flatness in the present invention is such that the intermediate transfer member is stretched by applying a load of 4 kg with two parallel shafts 18 (Φ28 mm), and the surface of the intermediate transfer member at that time is measured by a laser displacement meter 17. (Maximum value and minimum value of the displacement amount of the belt surface with the laser displacement meter 17 parallel to the axis at a position of 200 mm from the center of the shaft paired with the shaft stretched by (Keyence Corporation LK-030)) The difference is read.
[0029]
The intermediate transfer member of the present invention has a belt shape, and is particularly preferably a seamless belt (endless belt). In the case of this seamless belt, the thickness of the belt can be appropriately determined according to the purpose of use. In general, however, it is preferably about 20 to 500 μm, particularly preferably 50 to about 500 μm from mechanical properties such as strength and flexibility. 200 μm.
[0030]
Since such an intermediate transfer member has good flatness, it can be suitably used in a tandem image forming apparatus. The tandem type image forming apparatus does not repeat latent image formation, development, transfer, charge removal, and cleaning for each color, unlike the conventionally known transfer drum method and intermediate transfer method, and a plurality of image carriers are provided. Since they are arranged, there is an advantage that the image forming speed is remarkably improved. At this time, when the intermediate transfer member of the present invention is used, the flatness, surface roughness, and thickness accuracy are good, so that a good image can be obtained.
[0031]
(Image forming device)
The image forming apparatus of the present invention includes the intermediate transfer member of the present invention. For example, a photosensitive member 9 for each color including a developing device 15 of four colors (black, yellow, magenta, and cyan) is used as the intermediate transfer member 16. It can be applied to the arranged tandem color image forming apparatus. By providing the intermediate transfer member of the present invention, a high-quality transfer image can be obtained. Specifically, a charging roll 13 (charging device) that uniformly charges the surface of the photoconductor 9, a laser generator 8 (exposure device) that exposes the surface of the photoconductor 9 to form an electrostatic latent image, and the surface of the photoconductor 9 The formed latent image is developed using a developer, and a developing device 15 (developing device) for forming a toner image, a photoconductor cleaner 14 (cleaning device) for removing toner, dust, and the like attached to the photoconductor, and a transfer target A fixing roll 2 for fixing the toner image on the material can be optionally provided by a known method as necessary.
[0032]
As the image bearing member, a conventionally known one can be used, and as the photosensitive layer, a known one such as organic or amorphous silicon can be used. When the previous image carrier is cylindrical, it can be obtained by a known production method such as surface processing after extrusion molding of aluminum or an aluminum alloy. It is also possible to use the belt-shaped image carrier.
[0033]
The charging means is not particularly limited, and examples thereof include contact type chargers using conductive or semiconductive rollers, brushes, films, rubber blades, scorotron chargers and corotron chargers using corona discharge, etc. A charger known per se can be used. Among these, a contact-type charger is preferable in terms of excellent charge compensation capability. The charging unit normally applies a direct current to the electrophotographic photosensitive member, but an alternating current may be applied in a superimposed manner.
[0034]
The exposure means is not particularly limited. For example, the surface of the electrophotographic photosensitive member is exposed to a light source such as a semiconductor laser light, an LED light, a liquid crystal shutter light, or a desired image from these light sources through a polygon mirror. An optical system device that can be used.
[0035]
The developing means can be appropriately selected according to the purpose. For example, a known developing device that develops a one-component developer or a two-component developer in contact or non-contact with a brush, a roller, etc. Is mentioned.
[0036]
As the first transfer means, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade, etc., a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger Is mentioned. Among these, a contact type transfer charger is preferable in that it has excellent transfer charge compensation capability. In the present invention, in addition to the transfer charger, a peeling charger can be used in combination.
[0037]
Examples of the second transfer unit include a contact transfer charger such as a transfer roller exemplified as the first transfer unit, a scorotron transfer charger, a corotron transfer charger, and the like. Among these, a contact-type transfer charger is preferable like the first transfer unit. When the contact type transfer charger such as a transfer roller is pressed strongly, the image transfer state can be maintained in a good state. In addition, when a contact type transfer charger such as a transfer roller is pressed at the position of the roller that guides the intermediate transfer member, the toner image can be transferred from the intermediate transfer member to the transfer member in a good state. become.
[0038]
Examples of the light neutralizing means include tungsten lamps and LEDs. Examples of the light quality used in the light neutralizing process include white light such as tungsten lamps and red light such as LED light. The irradiation light intensity in the photostatic process is usually set to output several times to about 30 times the amount of light indicating the half exposure sensitivity of the electrophotographic photosensitive member.
[0039]
The cleaning means is not particularly limited, and a known cleaning device or the like may be used.
The fixing unit is not particularly limited, and examples thereof include known fixing devices such as a heat roller fixing device and an oven fixing device.
[0040]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.
[0041]
<Example 1>
Oxidized carbon black (Degussa Special Black 4) 3, 3 ', 4, 4'-biphenyltetracarboxylic acid (BPDA) and polyamic acid NMP solution consisting of p-phenylenediamine (PDA) was used as the inner surface of the cylindrical mold. Then, it is applied to 400 μm via a dispenser, rotated at 1500 rpm (15 minutes) to form a spread layer having a uniform thickness, and then heated at 60 ° C. from the outside of the mold while rotating at 250 rpm. Then, after heating at 150 ° C. for 60 minutes, it was returned to room temperature and molded. Thereafter, the cured polyamic acid belt is peeled off from the inner surface of the mold until it can be self-supported, replaced with the outer surface of an aluminum cylinder having a surface roughness (Ra) of 1.8 μm, and then increased to 250 ° C. at 2 ° C./min. After raising the temperature at a temperature rate and holding at 250 ° C. for 1 hour, the mixture was further heated to 300 ° C. at a rate of 2 ° C./min for 30 minutes to complete the imide conversion reaction. Thereafter, the temperature was returned to room temperature to obtain a target intermediate transfer belt. The belt thickness was 75 μm. Using this intermediate transfer belt, the image is mainly charged with triphenylamine for each color provided with toner for polyester-based DocuPrint C620 in a developing device 15 of four colors (black, yellow, magenta, cyan) shown in FIG. Image defects were evaluated using a tandem color image forming apparatus in which a photoreceptor 9 having a charge transport layer dispersed in polycarbonate as a transport agent and a phthalocyanine-based charge generation layer was disposed on the intermediate transfer member 16. The flatness of the intermediate transfer member is 200 mm from the center of the shaft by a laser displacement meter (LK-030 manufactured by Keyence) when the intermediate transfer member is stretched by a load of 4 kg with two parallel shafts (Φ28). The difference between the maximum value and the minimum value of the displacement amount of the belt surface was read by the laser displacement meter with the position parallel to the axis. The surface roughness of the aluminum cylinder and the intermediate transfer belt is measured according to JIS B601. As a result, the surface roughness of the obtained intermediate transfer belt was 1.4 μm and the image evaluation was performed with a flatness of 1.2 mm. As a result, a good image was obtained with no roughness or color shift.
[0042]
<Example 2>
Two types of oxidized carbon black were mixed to Example 1 (Degussa Special Black 4 and Degussa Special Black 250), and after the molding, the cured polyamic acid belt was peeled off until it could be self-supported. After replacing the outer surface of the aluminum cylinder having a surface roughness (Ra) of 1.4 μm, the temperature was increased to 250 ° C. at a rate of 2 ° C./min and held at 280 ° C. for 0.5 hours. Furthermore, it heated at 300 degreeC with the temperature increase rate of 2 degree-C / min for 30 minutes, and the imide conversion reaction was completed. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the obtained intermediate transfer belt was 1.2 μm, and image evaluation was performed with a flatness of 2.9 mm. As a result, good images were obtained with no roughness or color shift.
[0043]
<Example 3>
Two kinds of oxidized carbon black were mixed with Example 1 (Degussa Special Black 4 and Degussa Special Black 250), and 3, 3 ′, 4, 4′-biphenyltetracarboxylic acid (BPDA) was used. And polyamic acid NMP solution composed of p-phenylenediamine (PDA) and polyamic acid NMP solution composed of 3,3 ′, 4,4′-biphenyltetracarboxylic acid (BPDA) and oxydianiline (ODA) at 8: 2. After mixing, the cured polyamic acid belt is peeled off from the inner surface of the mold until it can be self-supported, and is replaced with the outer surface of an aluminum cylinder having a surface roughness (Ra) of 1.2 μm. After heating at 220 ° C. for 0.5 hour, further heating to 300 ° C. at a rate of 2 ° C./min for 30 minutes to complete the imide conversion reaction I went. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the obtained intermediate transfer belt was 0.9 μm and the image evaluation was performed with a flatness of 4.2 mm. As a result, there was no roughness and a slight color misregistration was observed but there was no problem.
[0044]
<Example 4>
Using oxidized carbon black (special black 4 manufactured by Degussa Co., Ltd.) in Example 1, the polyamic acid belt cured until it can be self-supported after molding is peeled off, and the surface roughness (Ra) is 2. After replacing the outer surface of a 0 μm aluminum cylinder, the temperature was increased to 250 ° C. at a rate of 2 ° C./min, held at 250 ° C. for 3.0 hours, and then further increased to 300 ° C. at 2 ° C./min. Heating at a speed for 30 minutes completed the imide conversion reaction. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the obtained intermediate transfer belt was 1.5 μm, and the image evaluation was performed with a flatness of 1.2 mm.
[0045]
<Example 5>
Two kinds of oxidized carbon black were mixed with Example 1 (Degussa Special Black 4 and Degussa Special Black 250), and 3, 3 ′, 4, 4′-biphenyltetracarboxylic acid (BPDA) was used. And polyamic acid NMP solution consisting of 3,3 ′, 4,4′-biphenyltetratetracarboxylic acid (BPDA) and oxydianiline (ODA) 8: 2 After the molding, the polyamic acid belt cured until it can be self-supported from the inner surface of the mold is peeled off and replaced with the outer surface of an aluminum cylinder having a surface roughness (Ra) of 1.5 μm. After heating at 220 ° C. for 0.7 hours, further heating to 300 ° C. at a rate of 2 ° C./min for 30 minutes to complete the imide conversion reaction. It was carried out. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the intermediate transfer belt obtained was 1.3 μm and the image evaluation was performed with a flatness of 3.8 mm. As a result, there was no roughness and a slight color misregistration was observed but there was no problem.
[0046]
<Example 6>
Using oxidized carbon black (special black 4 manufactured by Degussa Co., Ltd.) in Example 1, the polyamic acid belt cured until it can be self-supported after molding is peeled off, and the surface roughness (Ra) is 2. After replacing the outer surface of a 0 μm aluminum cylinder, the temperature was increased to 250 ° C. at a rate of 2 ° C./min, held at 250 ° C. for 1.0 hour, and further increased to 300 ° C. at 2 ° C./min. Heating at a speed for 30 minutes completed the imide conversion reaction. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the intermediate transfer belt obtained was 1.7 μm and the image evaluation was performed with a flatness of 1.2 mm.
[0047]
<Example 7>
Two kinds of oxidized carbon black were mixed with Example 1 (Degussa Special Black 4 and Degussa Special Black 250), and 3, 3 ′, 4, 4′-biphenyltetracarboxylic acid (BPDA) was used. And polyamic acid NMP solution consisting of 3,3 ′, 4,4′-biphenyltetratetracarboxylic acid (BPDA) and oxydianiline (ODA) 8: 2 After the molding, the polyamic acid belt cured until it can be self-supported from the inner surface of the mold is peeled off and replaced with the outer surface of an aluminum cylinder having a surface roughness (Ra) of 2.5 μm. After heating at 220 ° C. for 0.7 hours, further heating to 300 ° C. at a rate of 2 ° C./min for 30 minutes to complete the imide conversion reaction. It was carried out. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the obtained intermediate transfer belt was 1.8 μm, and the image evaluation was performed with a flatness of 4.0 mm. As a result, the roughness was very bad and a slight color misregistration was observed but not a problem. . However, after using the intermediate transfer member, traces of slight contact with other neighboring members were found at the end.
[0048]
[Comparative example]
<Comparative Example 1>
Using oxidized carbon black (special black 4 manufactured by Degussa Co., Ltd.) as in Example 1, the polyamic acid belt cured until it can be self-supported from the inner surface of the mold after peeling is peeled off, and the surface roughness (Ra) is 1. After replacing the outer surface of an 8 μm aluminum cylinder, the temperature was raised to 250 ° C. at a rate of 2 ° C./min, held at 230 ° C. for 0.4 hours, and then further raised to 300 ° C. at 2 ° C./min. Heating at a speed for 30 minutes completed the imide conversion reaction. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, when the surface roughness of the obtained intermediate transfer belt was 1.4 μm and the image evaluation was performed with a flatness of 5.3 mm, there was no roughness, but the image was clearly understood visually.
[0049]
<Comparative example 2>
Two kinds of oxidized carbon black were mixed with Example 1 (Degussa Special Black 4 and Degussa Special Black 250), and 3, 3 ′, 4, 4′-biphenyltetracarboxylic acid (BPDA) was used. And polyamic acid NMP solution consisting of 3,3 ′, 4,4′-biphenyltetratetracarboxylic acid (BPDA) and oxydianiline (ODA) 8: 2 After the molding, the polyamic acid belt cured until it can be self-supported from the inner surface of the mold is peeled off and replaced with the outer surface of an aluminum cylinder having a surface roughness (Ra) of 1.2 μm. After heating at 250 ° C. for 0.2 hours, further heating to 300 ° C. at a rate of 2 ° C./min for 30 minutes to complete the imide conversion reaction. It was carried out. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the obtained intermediate transfer belt was 0.9 μm, and the image evaluation was performed at a flatness of 6.0 mm. There was no roughness, but the color shift was clearly seen visually, and the intermediate transfer belt was otherwise Discharge occurred and the image was lost.
[0050]
<Comparative Example 3>
Using oxidized carbon black (special black 4 manufactured by Degussa Co., Ltd.) in Example 1, the polyamic acid belt cured until it can be self-supported after molding is peeled off, and the surface roughness (Ra) is 2. After replacing the outer surface of a 0 μm aluminum cylinder, the temperature was increased to 250 ° C. at a rate of 2 ° C./min, held at 200 ° C. for 0.5 hour, and then further increased to 300 ° C. at 2 ° C./min. Heating at a speed for 30 minutes completed the imide conversion reaction. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the intermediate transfer belt obtained was 1.5 μm and the image evaluation was performed with a flatness of 5.5 mm. Further, the end portion of the intermediate transfer member was in contact with a nearby member and was significantly damaged.
[0051]
<Comparative example 4>
Two types of oxidized carbon black were mixed to Example 1 (Degussa Special Black 4 and Degussa Special Black 250), and after the molding, the cured polyamic acid belt was peeled off until it could be self-supported. Then, after replacing the outer surface of the aluminum cylinder having a surface roughness (Ra) of 1.1 μm, the temperature was increased to 250 ° C. at a rate of 2 ° C./min and held at 280 ° C. for 0.2 hours. Furthermore, it heated at 300 degreeC with the temperature increase rate of 2 degree-C / min for 30 minutes, and the imide conversion reaction was completed. As for other conditions, an intermediate transfer belt was prepared in the same manner as in Example 1, and image evaluation was performed with a tandem color image forming apparatus, and surface roughness and flatness were measured. As a result, the surface roughness of the obtained intermediate transfer belt was 0.7 μm, and the image evaluation was performed with a flatness of 6.7 mm. Discharge occurred on contact with the member and image omission occurred.
[0052]
【The invention's effect】
As described above, according to the present invention, the intermediate transfer member used in the tandem intermediate transfer type image forming apparatus has a high degree of flatness and can thereby obtain a high-quality transfer image. And a manufacturing method thereof.
In addition, according to the present invention, it is possible to provide an intermediate transfer member having uniform electric resistance and high surface accuracy and thickness accuracy, and a manufacturing method thereof.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an image forming apparatus.
FIG. 2 is a schematic view of a measuring apparatus for measuring flatness.
[Explanation of symbols]
1 Toner cartridge
2 Fixing roll
3 Backup roll
4 Tension roll
5 Secondary transfer roll
6 Paper path
7 Paper tray
8 Laser generator
9 Photoconductor
10 Primary transfer roll
11 Drive roll
12 Transcription cleaner
13 Charging roll
14 Photoconductor cleaner
15 Developer
16 Intermediate transfer member
17 Laser displacement meter
18 Flatness meter belt tension shaft

Claims

Made of polyimide resin containing endless belt-like oxidized carbon black and biphenyl structure used in a tandem color image forming apparatus in which a plurality of image carriers having developing units for each color are arranged on an intermediate transfer member In the intermediate transfer member,
The heating step for converting the polyamic acid to imide, which is one step in the production process of the intermediate transfer body, includes heating conditions for holding at a heating temperature of 220 to 280 ° C. for 0.5 hour or longer, and the intermediate transfer An intermediate transfer member having a flatness of 5 mm or less when the body is stretched by applying a load of 4 kg on two parallel axes.

The intermediate transfer member according to claim 1, wherein the heating condition includes a condition in which the temperature is increased to a temperature of 2 ° C./min up to the heating temperature.

The intermediate transfer member according to claim 1 or 2, wherein the surface roughness (Ra) is 1.5 µm or less.

A method for producing an intermediate transfer member according to any one of claims 1 to 3 ,
The polyamic acid solution is supplied to the inner surface of the cylindrical mold and spread to form a coating, which is cured until it can be held as a belt by heating. Then, the belt is removed from the mold and replaced with the outer surface of the metal cylinder, and the imide conversion reaction is performed by heating. Including steps to perform,
The method for producing an intermediate transfer member, wherein the step of performing the imide conversion reaction includes a step of holding a heating temperature of 220 to 280 ° C. and a heating time of 0.5 hours or more.

A method for producing an intermediate transfer member according to any one of claims 1 to 3 ,
The polyamic acid solution is supplied to the inner surface of the cylindrical mold and spread to form a coating, which is cured until it can be held as a belt by heating. Then, the belt is removed from the mold and replaced with the outer surface of the metal cylinder, and the imide conversion reaction is performed by heating. Including steps to perform,
A method for producing an intermediate transfer member, wherein the metal cylinder outer surface has a surface roughness (Ra) of 1.2 to 2.0 μm.